The following excerpt discusses the spiritual rectification achieved by the Binding of Isaac. When the attribute of chesed (associated with Abraham) prevails in the world, then evil flourishes, for kindness allows even the wicked to exist. When the attribute of gevura (Isaac's quality) prevails in the world, even the righteous may be viewed as not completely worthy. These two qualities must therefore be balanced and harmonized. However even this is insufficient, for chesed and gevura may be balanced above in the supernal realms without it affecting this world. Therefore a third quality, tiferet, was given to Jacob. This restored the proper cosmic balance.

This text needs to be understood. It should have said,
"[G‑d tested] Isaac." Since Isaac was thirty-seven years old at the time, his father Abraham was not punishable [for Isaac's] reactions, so that if Isaac would have protested, and would have refused to cooperate [with Abraham], his father would not have been punished on his behalf.

Accordingly, this should be viewed as a test of Isaac's willingness to be offered as a sacrifice.

G‑d…gave Abraham the opportunity to acquire the quality of judgment, and thus become complete….

Why then is it written that G‑d tested Abraham, not Isaac? This was indeed Abraham's test, for G‑d [wanted to bring Abraham to perfection]. Thus He sought to blend Abraham with judgement [i.e. the sefira of gevura] of which there was no trace at all in Abraham prior to this.

Now, [once Abraham passed the test] water [chesed, kindness] would be blended with fire [gevura, din, severity].

Thus, after the test, the angel states, "Now I know that you fear G‑d"; (below, 22:12) fear as well as love.

Until this point, Abraham was not complete. Now water was blended with fire, and fire was blended with water.

Abraham attained the quality of gevura, and Isaac, who was willing to allow himself to become an offering, gained the quality of chesed.

This is why the verse states that G‑d tested Abraham. He gave Abraham the opportunity to acquire the quality of judgment, and thus become complete. When Abraham did so, fire blended into water and they complemented each other.

Now come and see the secret of this matter. Even though we have explained why it is written that G‑d tested Abraham and not Isaac, [nevertheless, note that] the verse uses the expression "v'haElokim nisa et Avraham".

The Talmud explains that 'et' indicates something in addition to the subject which the et precedes. In this way,Jacob came and rectified the situation completely….

Isaac is also included in this verse, in the words "et Abraham"; "et" refers to Isaac, who at that time remained below within [his attribute of gevura]. When he was bound [by his father and was placed on the altar, thus] providing Abraham with the opportunity to acquire [the attribute of din as explained above], he became crowned [while remaining] in his place together with Abraham.

Even though Isaac remained within his attribute of gevura without having to acquire the opposite attribute of chesed, nevertheless, through his willingness to be offered as a sacrifice his quality of severity was softened by the quality of loving-kindness.

He accomplished the blending of fire into water, and both of them ascended to a higher level. Then the division of fire and water was brought into the proper balance. Who ever saw a kindly father [Abraham] acting with [such apparent] cruelty?

This was because of the disharmony of fire and water within Abraham himself, which became balanced in their root above [through this action].

That is, until Jacob came and rectified the situation completely.

Jacob embodies the attribute of tiferet, the quality of harmony and truth.

Until Jacob's time, the attributes of fire and water (gevura and chesed, respectively) were only reconciled in their roots above, but not in the world below. Jacob, by bringing his attribute of truth into this world harmonized and balanced the attributes of Abraham and Isaac. The Sages state, "Jacob, who redeemed Abraham," and the Zohar also states in explaining the verse, "You command the salvations of Jacob" (Psalms 44:5) - salvations, in the plural form, which the Zohar interprets as the salvation of both Abraham and of Isaac.

Thus the three Patriarchs [Abraham, Isaac and Jacob] were brought to completion, and the upper and lower realms were rectified.

[From Zohar I, p. 119b-120a; translation and commentary by Moshe Miller]